Context-based grammars for automated speech recognition

ABSTRACT

Methods, apparatus, and computer program products for providing a context-based grammar for automatic speech recognition, including creating by a multimodal application a context, the context comprising words associated with user activity in the multimodal application, and supplementing by the multimodal application a grammar for automatic speech recognition in dependence upon the context.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the invention is data processing, or, more specifically,methods, apparatus, and products for providing a context-based grammarfor automatic speech recognition (‘ASR’).

2. Description of Related Art

User interaction with applications running on small devices through akeyboard or stylus has become increasingly limited and cumbersome asthose devices have become increasingly smaller. In particular, smallhandheld devices like mobile phones and PDAs serve many functions andcontain sufficient processing power to support user interaction throughother modes, such as multimodal access. Devices which support multimodalaccess combine multiple user input modes or channels in the sameinteraction allowing a user to interact with the applications on thedevice simultaneously through multiple input modes or channels. Themethods of input include speech recognition, keyboard, touch screen,stylus, mouse, handwriting, and others. Multimodal input often makesusing a small device easier.

Multimodal applications often run on servers that serve up multimodalweb pages for display on a multimodal browser. A ‘multimodal browser,’as the term is used in this specification, generally means a web browsercapable of receiving multimodal input and interacting with users withmultimodal output. Multimodal browsers typically render web pageswritten in XHTML+Voice (‘X+V’). X+V provides a markup language thatenables users to interact with an multimodal application often runningon a server through spoken dialog in addition to traditional means ofinput such as keyboard strokes and mouse pointer action. X+V adds spokeninteraction to standard web content by integrating XHTML (eXtensibleHypertext Markup Language) and speech recognition vocabularies supportedby VoiceXML. For visual markup, X+V includes the XHTML standard. Forvoice markup, X+V includes a subset of VoiceXML. For synchronizing theVoiceXML elements with corresponding visual interface elements, X+V usesevents. XHTML includes voice modules that support speech synthesis,speech dialogs, command and control, and speech grammars. Voice handlerscan be attached to XHTML elements and respond to specific events. Voiceinteraction features are integrated with XHTML and can consequently beused directly within XHTML content.

Current lightweight voice solutions require a developer to build agrammar and lexicon to limit the potential number of words that an ASRengine must recognize—as a means for increasing accuracy. Pervasivedevices have limited interaction and input modalities due to the formfactor of the device, and kiosk devices have limited interaction andinput modalities by design. In both cases the use of speaker independentvoice recognition is implemented to enhance the user experience andinteraction with the device. The state of the art in speaker independentrecognition allows for some sophisticated voice applications to bewritten as long as there is a limited vocabulary associated with eachpotential voice command. For example, if the user is prompted to speakthe name of a city the system can, with a decent level of confidence,recognize the name of the city spoken. In the case where there is noexplicit context, such as a blank text field for inputting any searchquery, this speaker independent recognition fails because a reasonablysized vocabulary is not available.

SUMMARY OF THE INVENTION

The disclosed invention seeks to overcome the limitations of the currentstate of the art in speaker independent voice recognition by dynamicallybuilding voice recognition grammars based on the context of a user'sactivities in a multimodal application. Methods, apparatus, and computerprogram products are described for providing a context-based grammar forautomatic speech recognition, including creating by a multimodalapplication a context, the context comprising words associated with useractivity in the multimodal application, and supplementing by themultimodal application a grammar for automatic speech recognition independence upon the context.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescriptions of exemplary embodiments of the invention as illustrated inthe accompanying drawings wherein like reference numbers generallyrepresent like parts of exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 sets forth a network diagram illustrating an exemplary system forproviding a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

FIG. 2 sets forth a block diagram of automated computing machinerycomprising an example of a computer useful as a voice server inproviding a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

FIG. 3 sets forth a block diagram of automated computing machinerycomprising an example of a computer useful as a multimodal device inproviding a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

FIG. 4 sets forth a functional block diagram of exemplary apparatus forproviding a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

FIG. 5 sets forth a functional block diagram of further exemplaryapparatus for providing a context-based grammar for automatic speechrecognition according to embodiments of the present invention.

FIG. 6 sets forth a flow chart illustrating an exemplary method ofproviding a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

FIG. 7 sets forth a flow chart illustrating a further exemplary methodof providing a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

FIG. 8 sets forth a flow chart illustrating a further exemplary methodof providing a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

FIG. 9 sets forth a flow chart illustrating a further exemplary methodof providing a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

FIG. 10 sets forth a flow chart illustrating a further exemplary methodof providing a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

FIG. 11 sets forth a line drawing illustrating an exemplary use case ofproviding a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary methods, apparatus, and products for providing a context-basedgrammar for automatic speech recognition according to embodiments of thepresent invention are described with reference to the accompanyingdrawings, beginning with FIG. 1. FIG. 1 sets forth a network diagramillustrating an exemplary system for providing a context-based grammarfor automatic speech recognition according to embodiments of the presentinvention. The system of FIG. 1 operates generally to provide acontext-based grammar for automatic speech recognition according toembodiments of the present invention by creating by a multimodalapplication a context, the context comprising words associated with useractivity in the multimodal application, and supplementing by themultimodal application a grammar for automatic speech recognition independence upon the context.

A multimodal device is an automated device, that is, automated computingmachinery or a computer program running on an automated device, that iscapable of accepting speech input from a user, digitizing speech, andproviding digitized speech to an ASR engine for recognition. Amultimodal device may be implemented, for example, as a voice-enabledbrowser on a laptop, a voice browser on a telephone handset, an onlinegame implemented with Java on a personal computer, and with othercombinations of hardware and software as may occur to those of skill inthe art.

The system of FIG. 1 includes several example multimodal devices:

-   -   personal computer (108) which is coupled for data communications        to data communications network (100) through wireline connection        (120),    -   personal digital assistant (‘PDA’) (112) which is coupled for        data communications to data communications network (100) through        wireless connection (114),    -   mobile telephone (110) which is coupled for data communications        to data communications network (100) through wireless connection        (116), and    -   laptop computer (126) which is coupled for data communications        to data communications network (100) through wireless connection        (118).

Each of the example multimodal devices (152) in the system of FIG. 1includes a microphone, an audio amplifier, a digital-to-analogconverter, and a multimodal application capable of accepting from a user(128) speech for recognition (315), digitizing the speech, and providingthe digitized speech to an ASR engine for recognition. The speech may bedigitized according to industry standard codecs, including but notlimited to those used for Distributed Speech Recognition as such.Methods for ‘COding/DECoding’ speech are referred to as ‘codecs.’ TheEuropean Telecommunications Standards Institute (‘ETSI’) providesseveral codecs for encoding speech for use in DSR, including, forexample, the ETSI ES 201 108 DSR Front-end Codec, the ETSI ES 202 050Advanced DSR Front-end Codec, the ETSI ES 202 211 Extended DSR Front-endCodec, and the ETSI ES 202 212 Extended Advanced DSR Front-end Codec. Instandards such as RFC3557 entitled

-   -   RTP Payload Format for European Telecommunications Standards        Institute (ETSI) European Standard ES 201 108 Distributed Speech        Recognition Encoding        and the Internet Draft entitled    -   RTP Payload Formats for European Telecommunications Standards        Institute (ETSI) European Standard ES 202 050, ES 202 211, and        ES 202 212 Distributed Speech Recognition Encoding,        the IETF provides standard RTP payload formats for various        codecs. It is useful to note, therefore, that there is no        limitation in the present invention regarding codecs, payload        formats, or packet structures. Speech for providing a        context-based grammar for automatic speech recognition according        to embodiments of the present invention may be encoded with any        codec, including, for example:    -   AMR (Adaptive Multi-Rate Speech coder)    -   ARDOR (Adaptive Rate-Distortion Optimized sound codeR),    -   Dolby Digital (A/52, AC3),    -   DTS (DTS Coherent Acoustics),    -   MP1 (MPEG audio layer-1),    -   MP2 (MPEG audio layer-2) Layer 2 audio codec (MPEG-1, MPEG-2 and        non-ISO MPEG-2.5),    -   MP3 (MPEG audio layer-3) Layer 3 audio codec (MPEG-1, MPEG-2 and        non-ISO MPEG-2.5),    -   Perceptual Audio Coding,    -   FS-1015 (LPC-10),    -   FS-1016 (CELP),    -   G.726 (ADPCM),    -   G.728 (LD-CELP),    -   G.729 (CS-ACELP),    -   GSM,    -   HILN (MPEG-4 Parametric audio coding), and    -   others as may occur to those of skill in the art.

An ASR engine (148) may be installed locally in the multimodal deviceitself, or an ASR engine (150) may be installed remotely with respect tothe multimodal device, across a data communications network (100) in avoice server (151). Each of the example multimodal devices (152) in thesystem of FIG. 1 is capable of providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention by creating by a multimodal application a context, the contextcomprising words associated with user activity in the multimodalapplication, and supplementing by the multimodal application a grammarfor automatic speech recognition in dependence upon the context.

The use of these four example multimodal devices (152) is forexplanation only, not for limitation of the invention. Any automatedcomputing machinery capable of accepting speech from a user, providingthe speech digitized to an ASR engine, and receiving and playing speechprompts and responses from the voice server may be improved to functionas a multimodal device for providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention.

The system of FIG. 1 also includes a voice server (151) which isconnected to data communications network (100) through wirelineconnection (122). The voice server (151) is a computer that runs aVoiceXML interpreter that provides voice recognition services formultimodal devices by accepting requests for speech recognition andreturning text representing recognized speech. Voice server (151) alsoprovides text to speech (‘TTS’) conversion for voice prompts and voiceresponses (314) to user input in multimodal applications such as, forexample, X+V applications or Java voice applications.

The system of FIG. 1 includes a data communications network (100) thatconnects the multimodal devices (152) and the voice server (151) fordata communications. A data communications network for providing acontext-based grammar for automatic speech recognition according toembodiments of the present invention is a data communications datacommunications network composed of a plurality of computers thatfunction as data communications routers connected for datacommunications with packet switching protocols. Such a datacommunications network may be implemented with optical connections,wireline connections, or with wireless connections. Such a datacommunications network may include intranets, internets, local area datacommunications networks (‘LANs’), and wide area data communicationsnetworks (‘WANs’). Such a data communications network may implement, forexample:

-   -   a link layer with the Ethernet™ Protocol or the Wireless        Ethernet™ Protocol,    -   a data communications network layer with the Internet Protocol        (‘IP’),    -   a transport layer with the Transmission Control Protocol (‘TCP’)        or the User Datagram Protocol (‘UDP’),    -   an application layer with the HyperText Transfer Protocol        (‘HTTP’), the Session Initiation Protocol (‘SIP’), the Real Time        Protocol (‘RTP’), the Distributed Multimodal Synchronization        Protocol (‘DMSP’), the Wireless Access Protocol (‘WAP’), the        Handheld Device Transfer Protocol (‘HDTP’), the ITU protocol        known as H.323, and    -   other protocols as will occur to those of skill in the art.

The arrangement of the voice server (151), the multimodal devices (152),and the data communications network (100) making up the exemplary systemillustrated in FIG. 1 are for explanation, not for limitation. Dataprocessing systems useful for providing a context-based grammar forautomatic speech recognition according to various embodiments of thepresent invention may include additional servers, routers, otherdevices, and peer-to-peer architectures, not shown in FIG. 1, as willoccur to those of skill in the art. Data communications networks in suchdata processing systems may support many data communications protocolsin addition to those noted above.

Various embodiments of the present invention may be implemented on avariety of hardware platforms in addition to those illustrated in FIG.1.

Providing a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention in some embodimentsmay be implemented with one or more voice servers, computers, that is,automated computing machinery, that provide speech recognition. Forfurther explanation, therefore, FIG. 2 sets forth a block diagram ofautomated computing machinery comprising an example of a computer usefulas a voice server (151) in providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention. The voice server (151) of FIG. 2 includes at least onecomputer processor (156) or ‘CPU’ as well as random access memory (168)(‘RAM’) which is connected through a high speed memory bus (166) and busadapter (158) to processor (156) and to other components of the voiceserver.

Stored in RAM (168) is a multimodal server application (188), a moduleof computer program instructions capable of operating a voice server ina system that is configured to provide a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention. Multimodal server application (188) provides voicerecognition services for multimodal devices by accepting requests forspeech recognition and returning speech recognition results, includingtext representing recognized speech, text for use as variable values indialogs, and text as string representations of scripts for semanticinterpretation. Multimodal server application (188) also includescomputer program instructions that provide text-to-speech (‘TTS’)conversion for voice prompts and voice responses to user input inmultimodal applications such as, for example, X+V applications or JavaSpeech applications. Multimodal server application (188) in this exampleis also configured to provide a context-based grammar for automaticspeech recognition according to embodiments of the present invention bycreating by a multimodal application a context, the context comprisingwords associated with user activity in the multimodal application, andsupplementing by the multimodal application a grammar for automaticspeech recognition in dependence upon the context.

Multimodal server application (188) in this example is a user-level,multimodal, server-side computer program that may be implemented with aset of VoiceXML documents which taken together comprise a VoiceXMLapplication. Multimodal server application (188) may be implemented as aweb server, implemented in Java, C++, or another language, that supportsX+V by providing responses to HTTP requests from X+V clients. Multimodalserver application (188) may, for a further example, be implemented as aJava server that runs on a Java Virtual Machine (102) and supports aJava voice framework by providing responses to HTTP requests from Javaclient applications running on multimodal devices. And multimodal serverapplications that support providing a context-based grammar forautomatic speech recognition may be implemented in other ways as mayoccur to those of skill in the art, and all such ways are well withinthe scope of the present invention.

The multimodal server application (188) in this example is configured toreceive speech for recognition from a user and pass the speech along toan ASR engine (150). ASR engine (150) is a module of computer programinstructions, also stored in RAM in this example, that includes an ASRlexicon (106) of words capable of recognition by the ASR engine. Thelexicon (106) is an association of words in text form with phonemesrepresenting pronunciations of each word. In carrying out automatedspeech recognition, the ASR engine receives speech for recognition inthe form of at least one digitized word, uses frequency components ofthe digitized word to derive a Speech Feature Vector (‘SFV’), uses theSFV to infer phonemes for the word from a language-specific acousticmodel (not shown). A language-specific acoustic model is a datastructure, a table or database, for example, that associates SFVs withphonemes representing, to the extent that it is practically feasible todo so, all pronunciations of all the words in a particular language. TheASR engine then uses the phonemes to find the word in the lexicon.

The ASR engine (150) contains an grammar (104). A grammar communicatesto an ASR engine the words and sequences of words that may berecognized. Grammars for use in providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention may be expressed in any format supported by any ASR engine,including, for example, the Java Speech Grammar Format (‘JSGF’), theformat of the W3C Speech Recognition Grammar Specification (‘SRGS’), theAugmented Backus-Naur Format (‘ABNF’) from the IETF's RFC2234, in theform of a stochastic grammar as described in the W3C's StochasticLanguage Models (N-Gram) Specification, and in other grammar formats asmay occur to those of skill in the art. Grammars typically operate aselements of dialogs, such as, for example, a VoiceXML <menu> or anX+V<form>. A grammar's definition may be expressed in-line in a dialog.Or the grammar may be implemented externally in a separate grammardocument and referenced from with a dialog with a URI. Here is anexample of a grammar expressed in JSFG:

<grammar scope=“dialog” ><![CDATA[   #JSGF V1.0;   grammar command;  <command> = [remind me to] call | phone | telephone <name>   <when>;  <name> = bob | martha | joe | pete | chris | john | artoush;   <when>= today | this afternoon | tomorrow | next week;   ]]> </grammar>

In this example, the elements named <command>, <name>, and <when> arerules of the grammar. Rules are a combination of a rulename and anexpansion of a rule that advises an ASR engine which words presently canbe recognized. In this example, expansion includes conjunction anddisjunction, and the vertical bars ‘|’ mean ‘or.’ An ASR engineprocesses the rules in sequence, first <command>, then <name>, then<when>. The <command> rule matches ‘call’ or ‘phone’ or ‘telephone’plus, that is, in conjunction with, whatever is returned from the <name>rule and the <when> rule. The <name> rule matches ‘bob’ or ‘martha’ or‘joe’ or ‘pete’ or ‘chris’ or ‘john’ or ‘artoush’, and the <when> rulematches ‘today’ or ‘this afternoon’ or ‘tomorrow’ or ‘next week.’ Thecommand grammar as a whole matches utterances like these, for example:

-   -   ‘phone bob next week,’    -   ‘telephone martha this afternoon,’    -   ‘remind me to call chris tomorrow,’ and    -   ‘remind me to phone pete today.’

Also stored in RAM is a VoiceXML interpreter (192), a module of computerprogram instructions that processes VoiceXML grammars. VoiceXML input toVoiceXML interpreter (192) may originate from VoiceXML clients runningremotely on multimodal devices, from X+V clients running remotely onmultimodal devices, or from Java client applications running remotely onmultimedia devices. In this example, VoiceXML interpreter (192)interprets and executes VoiceXML segments received from remotemultimedia clients and provided to VoiceXML interpreter (192) throughmultimodal server application (188). Also stored in RAM (168) is a TextTo Speech (‘TTS’) Engine (194), a module of computer programinstructions that accepts text as input and returns the same text in theform of digitally encoded speech, for use in providing speech as promptsfor and responses to users of multimodal systems.

Also stored in RAM (168) is an operating system (154). Operating systemsuseful in voice servers according to embodiments of the presentinvention include UNIX™, Linux™, Microsoft NT™, AIX™, IBM's i5/OS™, andothers as will occur to those of skill in the art. Operating system(154), multimodal server application (188), VoiceXML interpreter (192),ASR engine (150), JVM (102), and TTS Engine (194) in the example of FIG.2 are shown in RAM (168), but many components of such software typicallyare stored in non-volatile memory also, for example, on a disk drive(170).

Voice server (151) of FIG. 2 includes bus adapter (158), a computerhardware component that contains drive electronics for high speed buses,the front side bus (162), the video bus (164), and the memory bus (166),as well as drive electronics for the slower expansion bus (160).Examples of bus adapters useful in voice servers according toembodiments of the present invention include the Intel Northbridge, theIntel Memory Controller Hub, the Intel Southbridge, and the Intel I/OController Hub. Examples of expansion buses useful in voice serversaccording to embodiments of the present invention include IndustryStandard Architecture (‘ISA’) buses and Peripheral ComponentInterconnect (‘PCI’) buses.

Voice server (151) of FIG. 2 includes disk drive adapter (172) coupledthrough expansion bus (160) and bus adapter (158) to processor (156) andother components of the voice server (151). Disk drive adapter (172)connects non-volatile data storage to the voice server (151) in the formof disk drive (170). Disk drive adapters useful in voice servers includeIntegrated Drive Electronics (‘IDE’) adapters, Small Computer SystemInterface (‘SCSI’) adapters, and others as will occur to those of skillin the art. In addition, non-volatile computer memory may be implementedfor a voice server as an optical disk drive, electrically erasableprogrammable read-only memory (so-called ‘EEPROM’ or ‘Flash’ memory),RAM drives, and so on, as will occur to those of skill in the art.

The example voice server of FIG. 2 includes one or more input/output(‘I/O’) adapters (178). I/O adapters in voice servers implementuser-oriented input/output through, for example, software drivers andcomputer hardware for controlling output to display devices such ascomputer display screens, as well as user input from user input devices(181) such as keyboards and mice. The example voice server of FIG. 2includes a video adapter (209), which is an example of an I/O adapterspecially designed for graphic output to a display device (180) such asa display screen or computer monitor. Video adapter (209) is connectedto processor (156) through a high speed video bus (164), bus adapter(158), and the front side bus (162), which is also a high speed bus.

The exemplary voice server (151) of FIG. 2 includes a communicationsadapter (167) for data communications with other computers (182) and fordata communications with a data communications network (100). Such datacommunications may be carried out serially through RS-232 connections,through external buses such as a Universal Serial Bus (‘USB’), throughdata communications data communications networks such as IP datacommunications networks, and in other ways as will occur to those ofskill in the art. Communications adapters implement the hardware levelof data communications through which one computer sends datacommunications to another computer, directly or through a datacommunications network. Examples of communications adapters useful forproviding a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention include modems forwired dial-up communications, Ethernet (IEEE 802.3) adapters for wireddata communications network communications, and 802.11 adapters forwireless data communications network communications.

Providing a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention is generallyimplemented with one or more multimodal devices, that is, automatedcomputing machinery or computers. In the system of FIG. 1, for example,all the multimodal devices are implemented to some extent at least ascomputers. For further explanation, therefore, FIG. 3 sets forth a blockdiagram of automated computing machinery comprising an example of acomputer useful as a multimodal device (152) in providing acontext-based grammar for automatic speech recognition according toembodiments of the present invention. The multimodal device (152) ofFIG. 3 includes at least one computer processor (156) or ‘CPU’ as wellas random access memory (168) (‘RAM’) which is connected through a highspeed memory bus (166) and bus adapter (158) to processor (156) and toother components of the multimodal device.

Stored in RAM (168) is a multimodal device application (195), a moduleof computer program instructions capable of operating a multimodaldevice as an apparatus that supports providing a context-based grammarfor automatic speech recognition according to embodiments of the presentinvention. The multimodal device application (195) accepts speech forrecognition from a user and sends the speech for recognition through APIcalls to an ASR engine (150). Multimodal device application (195) inthis example is also configured to provide a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention by creating by a multimodal application a context, the contextcomprising words associated with user activity in the multimodalapplication, and supplementing by the multimodal application a grammarfor automatic speech recognition in dependence upon the context.

Multimodal device application (195) typically is a user-level,multimodal, client-side computer program that provides a speechinterface through which a user may provide oral speech for recognitionthrough microphone (176), have the speech digitized through an audioamplifier (185) and a coder/decoder (‘codec’) (183) of a sound card(174) and provide the digitized speech for recognition to ASR engine(150). The multimodal device application may be a Java voice applicationthat itself process grammars and provides grammars and digitized speechfor recognition directly through an API to an ASR engine (150). Or themultimodal device application may be an X+V application running in abrowser or microbrowser that passes VoiceXML grammars through API callsdirectly to an embedded VoiceXML interpreter (192) for processing. Theembedded VoiceXML interpreter (192) may in turn issue requests forspeech recognition through API calls directly to an embedded ASR engine(150). Multimodal device application (195) also provides TTS conversionby API calls to an embedded TTS engine (194) for voice prompts and voiceresponses to user input in multimodal applications such as, for example,X+V applications or Java voice applications. The multimodal deviceapplication (195) in this example does not send speech for recognitionacross a network to a voice server for recognition, and the multimodaldevice application (195) in this example does not receive TTS promptsand responses across a network from a voice server. All grammarprocessing, voice recognition, and text to speech conversion in thisexample is performed in an embedded fashion in the multimodal deviceitself.

ASR engine (150), also stored in RAM in this example, is a module ofcomputer program instructions for carrying out automated speechrecognition. An example of an embedded ASR engine that may be improvedfor providing a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention is IBM's EmbeddedViaVoice Enterprise, an ASR product that also includes an embedded TTSengine. The ASR engine (150) includes a grammar (104) that in turn asdescribed above includes rules defining which words and sequences ofwords are presently scoped for recognition. The ASR engine (150)includes an ASR lexicon (106) of words capable of recognition by the ASRengine.

Also stored in RAM (168) is an embedded TTS Engine (194), a module ofcomputer program instructions that accepts text as input and returns thesame text in the form of digitally encoded speech, for use in providingspeech as prompts for and responses to users of multimodal systems. TTSEngine (194) also supports providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention by providing a time-domain digitized form of a word spelled bya user to be added to the ASR lexicon (106).

Also stored in RAM (168) is an operating system (154). Operating systemsuseful in voice servers according to embodiments of the presentinvention include UNIX™, Linux™, Microsoft NT™, AIX™, IBM's i5/OS™, andothers as will occur to those of skill in the art. Operating system(154), multimodal device application (195), VoiceXML interpreter (192),ASR engine (150), JVM (102), and TTS Engine (194) in the example of FIG.2 are shown in RAM (168), but many components of such software typicallyare stored in non-volatile memory also, for example, on a disk drive(170).

The multimodal device (152) of FIG. 3 includes a bus adapter (158), acomputer hardware component that contains drive electronics for the highspeed buses, the front side bus (162), the video bus (164), and thememory bus (166), as well as for the slower expansion bus (160).Examples of bus adapters useful in multimodal devices according toembodiments of the present invention include the Intel Northbridge, theIntel Memory Controller Hub, the Intel Southbridge, and the Intel I/OController Hub. Examples of expansion buses useful in multimodal devicesaccording to embodiments of the present invention include IndustryStandard Architecture (‘ISA’) buses and Peripheral ComponentInterconnect (‘PCI’) buses.

Multimodal device (152) of FIG. 3 includes disk drive adapter (172)coupled through expansion bus (160) and bus adapter (158) to processor(156) and other components of the multimodal device (152). Disk driveadapter (172) connects non-volatile data storage to the multimodaldevice (152) in the form of disk drive (170). Disk drive adapters usefulin multimodal devices include Integrated Drive Electronics (‘IDE’)adapters, Small Computer System Interface (‘SCSI’) adapters, and othersas will occur to those of skill in the art. In addition, non-volatilecomputer memory may be implemented for a multimodal device as an opticaldisk drive, electrically erasable programmable read-only memory space(so-called ‘EEPROM’ or ‘Flash’ memory), RAM drives, and so on, as willoccur to those of skill in the art.

The example multimodal device of FIG. 3 includes one or moreinput/output (‘I/O’) adapters (178). I/O adapters in multimodal devicesimplement user-oriented input/output through, for example, softwaredrivers and computer hardware for controlling output to display devicessuch as computer display screens, as well as user input from user inputdevices (181) such as keyboards and mice. The example multimodal deviceof FIG. 3 includes video adapter (209), which is an example of an I/Oadapter specially designed for graphic output to a display device (180)such as a display screen or computer monitor. Video adapter (209) isconnected to processor (156) through a high speed video bus (164), busadapter (158), and the front side bus (162), which is also a high speedbus.

The example multimodal device of FIG. 3 also includes a sound card(174), which is an example of an I/O adapter specially designed foraccepting analog audio signals from a microphone (176) and convertingthe audio analog signals to digital form for further processing by acodec (183). The sound card (174) is connected to processor (156)through expansion bus (160), bus adapter (158), and front side bus(162).

The exemplary multimodal device (152) of FIG. 3 includes acommunications adapter (167) for data communications with othercomputers (182) and for data communications with data communicationsnetwork (100). Such data communications may be carried out throughserially through RS-232 connections, through external buses such as aUniversal Serial Bus (‘USB’), through data communications datacommunications networks such as IP data communications networks, and inother ways as will occur to those of skill in the art. Communicationsadapters implement the hardware level of data communications throughwhich one computer sends data communications to another computer,directly or through a data communications network. Examples ofcommunications adapters useful for providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention include modems for wired dial-up communications, Ethernet(IEEE 802.3) adapters for wired data communications networkcommunications, and 802.11b adapters for wireless data communicationsnetwork communications.

For further explanation, FIG. 4 sets forth a functional block diagram ofexemplary apparatus for providing a context-based grammar for automaticspeech recognition according to embodiments of the present invention.The example of FIG. 4 includes a multimodal device (152) and a voiceserver (151) connected for data communication by a VOIP connection (216)through a data communications network (100). A multimodal deviceapplication (195) runs on the multimodal device (152), and a multimodalserver application (188) runs on the voice server (151). The voiceserver (151) also has installed upon it an ASR engine (150) with angrammar (104) and an ASR lexicon (106), a JVM (102), and a Voice XMLinterpreter (192).

VOIP, standing for ‘Voice Over Internet Protocol,’ is a generic term forrouting speech over an IP-based data communications network. The speechdata flows over a general-purpose packet-switched data communicationsnetwork, instead of traditional dedicated, circuit-switched voicetransmission lines. Protocols used to carry voice signals over the IPdata communications network are commonly referred to as ‘Voice over IP’or ‘VOIP’ protocols. VOIP traffic may be deployed on any IP datacommunications network, including data communications networks lacking aconnection to the rest of the Internet, for instance on a privatebuilding-wide local area data communications network or ‘LAN.’

Many protocols are used to effect VOIP. The two most popular types ofVOIP are effected with the IETF's Session Initiation Protocol (‘SIP’)and the ITU's protocol known as ‘H.323.’ SIP clients use TCP and UDPport 5060 to connect to SIP servers. SIP itself is used to set up andtear down calls for speech transmission. VOIP with SIP then uses RTP fortransmitting the actual encoded speech. Similarly, H.323 is an umbrellarecommendation from the standards branch of the InternationalTelecommunications Union that defines protocols to provide audio-visualcommunication sessions on any packet data communications network.

The apparatus of FIG. 4 operates in a manner that is similar to theoperation of the system of FIG. 2 described above. Multimodal deviceapplication (195) presents a voice interface to user (128), providingaudio prompts and responses (314) and accepting speech for recognition(315). Multimodal device application (195) digitizes the speech forrecognition according to some codec, packages the speech in arecognition request message according to a VOIP protocol, and transmitsthe speech to voice server (151) through the VOIP connection (216) onthe network (100). Multimodal server application (188) provides voicerecognition services for multimodal devices by accepting requests forspeech recognition and returning speech recognition results, includingtext representing recognized speech, text for use as variable values indialogs, and text as string representations of scripts for semanticinterpretation. Multimodal server application (188) includes computerprogram instructions that provide text-to-speech (‘TTS’) conversion forvoice prompts and voice responses to user input in multimodalapplications such as, for example, X+V applications or Java Speechapplications.

The multimodal server application (188) receives speech for recognitionfrom a user and passes the speech to an ASR engine (150) forrecognition. The ASR engine receives digitized speech for recognition,uses frequency components of the digitized speech to derive an SFV, usesthe SFV to infer phonemes for the word from a language-specific acousticmodel (not shown), and uses the phonemes to find the speech in thelexicon (106). In addition in this example, multimodal serverapplication (188) is configured to provide a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention by creating by a multimodal application a context, the contextcomprising words associated with user activity in the multimodalapplication, and supplementing by the multimodal application a grammarfor automatic speech recognition in dependence upon the context.

VoiceXML interpreter (192) is a module of computer program instructionsthat processes VoiceXML grammars. In this example, VoiceXML interpreter(192) interprets and executes VoiceXML grammars received from themultimodal device application and provided to VoiceXML interpreter (192)through multimodal server application (188). VoiceXML input to VoiceXMLinterpreter (192) may originate from the multimodal device application(195) implemented as a VoiceXML client running remotely the multimodaldevice (152), from the multimodal device application (195) implementedas an X+V client running remotely on the multimodal device (152), orfrom the multimedia device application (195) implemented as a Javaclient application running remotely on the multimedia device (152).

The TTS Engine (194) is a module of computer program instructions thatin addition to providing digitized speech for use as prompts for andresponses (314) to user (128), also supports providing a context-basedgrammar for automatic speech recognition according to embodiments of thepresent invention by providing a time-domain digitized form of a wordspelled by a user to be added to the ASR lexicon (106).

For further explanation, FIG. 5 sets forth a functional block diagram offurther exemplary apparatus for providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention. In the example of FIG. 5, there is only a multimodal device(152) and a user (128), no network, no VOIP connection, and no voiceserver containing a remote ASR engine. All the components needed forproviding a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention are installed orembedded in the multimodal device itself, a laptop, a PDA, a cell phone,or the like.

The apparatus of FIG. 5 operates in a manner similar to the system ofFIG. 3. Multimodal device application (195) is a module of computerprogram instructions capable of operating a multimodal device as anapparatus that provides a context-based grammar for automatic speechrecognition according to embodiments of the present invention. Themultimodal device application (195) accepts speech for recognition froma user and sends the speech for recognition through API (179) to anembedded ASR engine (150). In addition in this example, multimodaldevice application (195) in this example is also configured to provide acontext-based grammar for automatic speech recognition according toembodiments of the present invention by creating by a multimodalapplication a context, the context comprising words associated with useractivity in the multimodal application, and supplementing by themultimodal application a grammar for automatic speech recognition independence upon the context.

Multimodal device application (195) is a user-level, multimodal,client-side computer program that provides a speech interface throughwhich a user may provide oral speech for recognition through microphone(176), have the speech digitized through an audio amplifier and a codec,and provide the digitized speech for recognition to the embedded ASRengine (150). The multimodal device application may be a Java voiceapplication that itself process grammars and provides grammars anddigitized speech for recognition directly through API (179) to theembedded ASR engine (150). Or the multimodal device application may bean X+V application running in a browser or microbrowser that passesVoiceXML grammars through API (175) to an embedded VoiceXML interpreter(192) for processing. The embedded VoiceXML interpreter (192) may inturn issue requests for speech recognition through API (179) to theembedded ASR engine (150). Multimodal device application (195) alsoprovides TTS conversion by API calls to an embedded TTS engine (194) forvoice prompts and voice responses to user input in multimodalapplications such as, for example, X+V applications or Java voiceapplications. The multimodal device application (195) in this exampledoes not send speech for recognition across a network to a voice serverfor recognition, and the multimodal device application (195) in thisexample does not receive TTS prompts and responses across a network froma voice server. All grammar processing, voice recognition, and text tospeech conversion is performed in an embedded fashion in the multimodaldevice itself.

Embedded ASR engine (150) is a module of computer program instructionsfor carrying out automated speech recognition. As mentioned, IBM'sEmbedded ViaVoice Enterprise, an ASR product that also includes anembedded TTS engine, is an example of an embedded ASR engine that may beimproved for providing a context-based grammar for automatic speechrecognition according to embodiments of the present invention. The ASRengine (150) includes an grammar (104) that in turn includes rulesdefining which words and sequences of words are presently scoped forrecognition. The ASR engine (150) includes an ASR lexicon (106) of wordscapable of recognition by the ASR engine.

The embedded TTS Engine (194) is a module of computer programinstructions that in addition to providing digitized speech for use asprompts for and responses to user (128), also supports providing acontext-based grammar for automatic speech recognition according toembodiments of the present invention by providing a time-domaindigitized form of a word spelled by a user to be added to the ASRlexicon (106).

For further explanation, FIG. 6 sets forth a flow chart illustrating anexemplary method of providing a context-based grammar for automaticspeech recognition according to embodiments of the present invention.The method of FIG. 6 includes creating (302) by a multimodal application(189) a context (304). The multimodal application (189) may be amultimodal server application like the one described above with regardto reference (188) on FIG. 4. The multimodal application (189) may be amultimodal device application like the one described above with regardto reference (195) on FIG. 5. Or the multimodal application (189) may beany other multimodal application as may occur to those of skill in theart. The context (304) is implemented as a data structure in which isstored words associated with user activity in the multimodalapplication, for example, words uttered by a user as speech forrecognition or words found on web sites previously visited by the userin operating the multimodal application. The context (304) may beimplemented as any data structure as may occur to those of skill in theart that is useful for storing words as computer data, a flat file, alinked list in RAM, a table, and so on.

In the method of FIG. 6, creating (310) a context is carried out byinserting (310) in the context one or more words from a grammar (105)from a previously visited multimodal web page (308). In this example,the previously visited web pages are multimodal in the sense that theycontain grammars that in turn contain words that are capable of beinginserted into a context and later used for insertion from the contextinto another grammar.

The method of FIG. 6 also includes supplementing (306) by the multimodalapplication (189) a grammar (104) for automatic speech recognition independence upon the context (304). The multimodal application (189)supplements (306) a grammar (104) in dependence upon the context (304)by adding to the grammar (104) words from the context (304) and theninstructing an ASR engine (150) to compile the grammar into a lexicon(106) to assure that all the words now in the grammar are also in thelexicon that supports recognition of words in that particular grammar.The embedded ASR engine may compile the grammar by converting with a TTSengine (194) the entire grammar into time-domain digitized words,converting the digitized words to the frequency domain, defining SFVsfor the words, inferring phonemes for the words from a language-specificacoustic model, and inserting the text forms of the words and thephonemes for the words into the lexicon.

For further explanation, FIG. 7 sets forth a flow chart illustrating afurther exemplary method of providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention. In the method of FIG. 7, multimodal application (189)supplements (306) a grammar (104) for automatic speech recognition independence upon the context (304) as described above in the method ofFIG. 6. That is, the multimodal application (189) adds words from thecontext (304) to the grammar (104), instructs an ASR engine (150) tocompile the grammar into a lexicon (106), and so on, as described above.

In the method of FIG. 7, however, creating (302) a context isimplemented by maintaining (316) a history (314) of words frompreviously visited web pages (312) and selecting (318) words for thecontext from the history. The web pages contain words. In this example,words are taken directly from any web page text, not exclusively from agrammar of a web page. So in this example the previously visited webpages may not be multimodal web pages. The history (314) is implementedas a data structure in which is stored words from previously visited webpages. The history (314) may be implemented as any data structure as mayoccur to those of skill in the art that is useful for storing words ascomputer data, a flat file, a linked list in RAM, a table, and so on.

For further explanation, FIG. 8 sets forth a flow chart illustrating afurther exemplary method of providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention. In the method of FIG. 8, multimodal application (189)supplements (306) a grammar (104) for automatic speech recognition independence upon the context (304) as described above in the method ofFIG. 6. That is, the multimodal application (189) adds words from thecontext (304) to the grammar (104), instructs an ASR engine (150) tocompile the grammar into a lexicon (106), and so on, as described above.

In the method of FIG. 8, however, creating (302) a context (304) iscarried out by maintaining (316) a history (314) of words frompreviously visited web pages (312), generating (320) a frequent valueslist (322) for words in the history, and selecting (324) words for thecontext from the history in dependence upon the frequent values list.The frequent values list (322) associates each word in the list with acount of the number of times the word occurs in the previously visitedweb pages. The frequent values list (322) is implemented as a datastructure in which is stored words from previously visited web pagesalong with associated counts of occurrences. The frequent values list(322) may be implemented as any data structure as may occur to those ofskill in the art that is useful for storing words as computer data inassociation with counts of occurrences, a flat file, a linked list inRAM, a table, and so on.

Selecting (324) words for the context from the history in dependenceupon the frequent values list may be carried out by selecting wordshaving occurrence counts exceeding a predetermined threshold. Themultimodal application (189) may, for example, select only words thatoccur at least five times in the previously visited web pages, therebyimproving the relevance of words used to supplement (306) the grammar(104).

For further explanation, FIG. 9 sets forth a flow chart illustrating afurther exemplary method of providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention. In the method of FIG. 9, multimodal application (189)supplements (306) a grammar (104) for automatic speech recognition independence upon the context (304) as described above in the method ofFIG. 6. That is, the multimodal application (189) adds words from thecontext (304) to the grammar (104), instructs an ASR engine (150) tocompile the grammar into a lexicon (106), and so on, as described above.

In the method of FIG. 9, however, creating (302) a context (304) iscarried out by maintaining (316) a history (314) of words frompreviously visited web pages (312), generating (326) a list (328) ofmost recently used words in the history, and selecting (330) words forthe context (304) from the history in dependence upon the list of mostrecently used words. Generating (326) a list of most recently used wordsin the history may be implemented by storing words from previouslyvisited web pages in association with time stamps indicating the mostrecent time when a user uttered the word as speech for recognition andthe word was recognized by the ASR engine (150). The list (328) of mostrecently used words is implemented as a data structure in which isstored words from previously visited web pages along with associatedusage times. The list (328) of most recently used words may beimplemented as any data structure as may occur to those of skill in theart that is useful for storing words as computer data in associationwith usage times, that is, a flat file, a linked list in RAM, a table,and so on.

Selecting (330) words for the context (304) from the history independence upon the list of most recently used words may be carried outby selecting words having usage times no earlier than a predeterminedthreshold. The multimodal application (189) may, for example, selectonly words that have been used within the last five minutes, therebyimproving the relevance of words used to supplement (306) the grammar(104).

For further explanation, FIG. 10 sets forth a flow chart illustrating afurther exemplary method of providing a context-based grammar forautomatic speech recognition according to embodiments of the presentinvention. In the method of FIG. 10, multimodal application (189)supplements (306) a grammar (104) for automatic speech recognition independence upon the context (304) as described above in the method ofFIG. 6. That is, the multimodal application (189) adds words from thecontext (304) to the grammar (104), instructs an ASR engine (150) tocompile the grammar into a lexicon (106), and so on, as described above.

In the method of FIG. 10, however, creating (302) a context (304)further comprises maintaining (316) a history (314) of words frompreviously visited web pages (312), generating (332) a list (334) ofwords from the history used during a predetermined period of time, andselecting (336) words for the context (304) from the history (314) independence upon the list (334) of words from the history used during apredetermined period of time. Generating (332) a list (334) of wordsfrom the history used during a predetermined period of time may beimplemented by storing words from previously visited web pages inassociation with time stamps indicating when a user uttered the word asspeech for recognition and the word was recognized by the ASR engine(150). In this way, multiple instances of the word are recorded if theword is spoken and recognized more than once during the period. The list(334) of words from the history used during a predetermined period oftime is implemented as a data structure in which is stored words frompreviously visited web pages along with associated usage times. The list(334) of words from the history used during a predetermined period oftime may be implemented as any data structure as may occur to those ofskill in the art that is useful for storing words as computer data inassociation with usage times, that is, a flat file, a linked list inRAM, a table, and so on.

Selecting (336) words for the context (304) from the history (314) independence upon the list (334) of words from the history used during apredetermined period of time may be carried out by setting thepredetermined period to improve the relevance of words used tosupplement (306) the grammar (104). During the work week, when a user isusing a multimodal application such as a multimodal browser primarilyfor work-related tasks, the user may set the predetermined period asMonday morning through Friday afternoon, thereby supplementing thegrammar during the work week with work-related words. During theweekend, when a user is using a multimodal application such as amultimodal browser primarily for recreational purposes, the user may setthe predetermined period as Friday evening through Sunday evening,thereby supplementing the grammar over the weekend with hobby-relatedwords.

For further explanation, FIG. 11 sets forth a line drawing illustratingan exemplary use case of providing a context-based grammar for automaticspeech recognition according to embodiments of the present invention.The use case of FIG. 11 includes user activity with a microbrowser on acell phone navigating to four X+V web sites, an Acura dealership website (402), a BMW dealership web site (404), a Volvo dealership website, and the Google™ web site (408). From the Acura web site, possiblespoken queries include:

“Show me a quote for an RL” “Compare the Acura RL and the BMW Z4” “Findan Acura Dealer in Palm Beach, Florida”

These could be implemented with the following grammar in an X+V page:

<command> = <quote> | <compare> | <find-dealer> <quote> = [Show|Display] [a] quote [for] [a|an] <model> <compare> = Compare [a|an] <model> and[a|an] <model> <find-dealer> = Find|show [a] dealer [in] <location><model> = [Acura] RL|TL|RSX|TSX|MDX <location> = <city> |<city> <state>| <zipcode>

The automobile dealership web sites are examples of domain-specific websites, web sites dedicated to a particular subject matter. The Googleweb site is a generic search page; it supports searches foranything—with no domain specificity. A generic search page is a web pagethat operates a search engine such as Google™, Yahoo™, or Ask.com™,having a generic search data entry field, that is, a data entry fieldthat supports no more than general search commands such as, for example,“search” or “find” or “go.” That is, the supported voice search commandsin a generic search page include no domain-specific voice commands, novoice commands to search for automobile parts or wool socks or linentable napkins.

As pages are visited in the domain-specific automobile web sites, thegrammars, or words from the grammars, that are in the X+V pages arestored in a context so that they could all be used to supplement agrammar at a generic search page. Then the utterance “Compare the AcuraRL and the BMW Z4” or “Find an Acura Dealer in Palm Beach, Fla.” may berecognized and entered as a search term in a generic search field of ageneric search page.

Additionally, a multimodal application that collects vocabulary fromhistory could build a grammar by accumulating keywords, as in thefollowing:

<search> = [search|find|look for] <search-string> <search-string> =<keyword> [<keyword>]* <keyword> =Acura|NSX|RSX|TSX|transmission|brakes|steering|    alloy|Volvo|S80|S60|S40|X90|roof rack|traction ...

So that following the user's web history above, the generic search pagecould recognize a phrase such as: “Look for Acura roof racks.”

In view of the explanations set forth above in this paper, readers willrecognize that providing a context-based grammar for automatic speechrecognition according to embodiments of the present invention overcomesthe limitations of the current state of the art in speaker independentvoice recognition by dynamically building grammars based on the contextof a user's activities. A system that provides a context-based grammarfor automatic speech recognition according to embodiments of the presentinvention augments existing speaker independent voice recognitionengines by dynamically providing grammars, where they are otherwiseunavailable, based on the users previous context of activity on thesystem. For a user who spent the last few minutes browsing automobileweb sites, for example, now opens a Google™ search window, a system thatprovides a context-based grammar for automatic speech recognitionaccording to embodiments of the present invention effectively assumesthat the search is related to automobiles and provides a voicerecognition grammar that contains car names, makes, models, along withvarious other terms encountered in users browsing. As another example:For a user interacting with a system management console for a Z Systemmainframe who moves to a user group web site to do a search, the grammarfor voice commands in that search box would be generated based on thetext encountered in the system management console.

Exemplary embodiments of the present invention are described largely inthe context of a fully functional computer system for providing acontext-based grammar for automatic speech recognition. Readers of skillin the art will recognize, however, that the present invention also maybe embodied in a computer program product disposed on signal bearingmedia for use with any suitable data processing system. Such signalbearing media may be transmission media or recordable media formachine-readable information, including magnetic media, optical media,or other suitable media. Examples of recordable media include magneticdisks in hard drives or diskettes, compact disks for optical drives,magnetic tape, and others as will occur to those of skill in the art.Examples of transmission media include telephone data communicationsnetworks for voice communications and digital data communications datacommunications networks such as, for example, Ethernets™ and datacommunications networks that communicate with the Internet Protocol andthe World Wide Web. Persons skilled in the art will immediatelyrecognize that any computer system having suitable programming meanswill be capable of executing the steps of the method of the invention asembodied in a program product. Persons skilled in the art will recognizeimmediately that, although some of the exemplary embodiments describedin this specification are oriented to software installed and executingon computer hardware, nevertheless, alternative embodiments implementedas firmware or as hardware are well within the scope of the presentinvention.

It will be understood from the foregoing description that modificationsand changes may be made in various embodiments of the present inventionwithout departing from its true spirit. The descriptions in thisspecification are for purposes of illustration only and are not to beconstrued in a limiting sense. The scope of the present invention islimited only by the language of the following claims.

1. A method of providing a context-based grammar for automatic speechrecognition at a first web page, the method comprising: creating by amultimodal application a context, the context comprising words takenfrom at least one second web page different from the first web page,and/or taken from at least one grammar for the at least one second webpage, wherein creating the context comprises maintaining a history of atleast some words from previously visited web pages, generatingoccurrence counts for words in the history, and selecting words for thecontext based at least in part on the occurrence counts; andsupplementing by the multimodal application a grammar and/or lexicon forautomatic speech recognition at the first web page in dependence uponthe context.
 2. The method of claim 1, wherein creating the contextfurther comprises inserting in the context one or more words from agrammar from a previously visited multimodal web page.
 3. The method ofclaim 1, wherein creating the context further comprises selecting wordsfor the context from the history.
 4. The method of claim 1, whereincreating the context further comprises generating a frequent values listfor words in the history, and selecting words for the context from thehistory in dependence upon the frequent values list.
 5. The method ofclaim 1, wherein creating the context further comprises generating alist of most recently used words in the history, and selecting words forthe context from the history in dependence upon the list of mostrecently used words.
 6. The method of claim 1, wherein creating thecontext further comprises generating a list of words from the historyused during a predetermined period of time, and selecting words for thecontext from the history in dependence upon the list of words from thehistory used during a predetermined period of time.
 7. The method ofclaim 1, wherein the grammar is a VoiceXML grammar.
 8. The method ofclaim 1, wherein the multimodal application runs on a voice server. 9.The method of claim 1, further comprising: inferring at least onephoneme for at least one word in the grammar using text to speechconversion; and adding the at least one phoneme for the at least oneword to the lexicon.
 10. The method of claim 1, wherein the contextcomprises words taken from the at least one second web page.
 11. Themethod of claim 1, wherein the context comprises words taken from atleast one grammar for the at least one second web page.
 12. A system forproviding a context-based grammar for automatic speech recognition at afirst web page, the system comprising a computer processor and acomputer memory operatively coupled to the computer processor, thecomputer memory having disposed within it computer program instructionscapable of: creating by a multimodal application a context, the contextcomprising words taken from at least one second web page different fromthe first web page, and/or taken from at least one grammar for the atleast one second web page, wherein creating the context comprisesmaintaining a history of at least some words from previously visited webpages, generating occurrence counts for words in the history, andselecting words for the context based at least in part on the occurrencecounts; and supplementing by the multimodal application a grammar and/orlexicon for automatic speech recognition at the first web page independence upon the context.
 13. The system of claim 12, whereincreating the context further comprises inserting in the context one ormore words from a grammar from a previously visited multimodal web page.14. The system of claim 12, wherein creating the context furthercomprises selecting words for the context from the history.
 15. Thesystem of claim 12, wherein creating the context further comprisesgenerating a frequent values list for words in the history, andselecting words for the context from the history in dependence upon thefrequent values list.
 16. The system of claim 12, wherein creating thecontext further comprises generating a list of most recently used wordsin the history, and selecting words for the context from the history independence upon the list of most recently used words.
 17. The system ofclaim 12, wherein creating the context further comprises generating alist of words from the history used during a predetermined period oftime, and selecting words for the context from the history in dependenceupon the list of words from the history used during a predeterminedperiod of time.
 18. The system of claim 12, wherein the grammar is aVoiceXML grammar.
 19. The system of claim 12, wherein the multimodalapplication runs on a voice server.
 20. The system of claim 12, whereinthe computer program instructions are further capable of: inferring atleast one phoneme for at least one word in the grammar using text tospeech conversion; and adding the at least one phoneme for the at leastone word to the lexicon.
 21. The system of claim 12, wherein the contextcomprises words taken from the at least one second web page.
 22. Thesystem of claim 12, wherein the context comprises words taken from atleast one grammar for the at least one second web page.
 23. A computerprogram product for providing a context-based grammar for automaticspeech recognition at a first web page, the computer program productcomprising at least one recordable medium storing computer programinstructions that, when executed, perform acts of: creating by amultimodal application a context, the context comprising words takenfrom at least one second web page different from the first web page,and/or taken from at least one grammar for the at least one second webpage, wherein creating the context comprises maintaining a history of atleast some words from previously visited web pages, generatingoccurrence counts for words in the history, and selecting words for thecontext based at least in part on the occurrence counts; andsupplementing by the multimodal application a grammar and/or lexicon forautomatic speech recognition at the first web page in dependence uponthe context.
 24. The computer program product of claim 23, whereincreating the context further comprises inserting in the context one ormore words from a grammar from a previously visited multimodal web page.25. The computer program product of claim 23, wherein creating thecontext further comprises selecting words for the context from thehistory.
 26. The computer program product of claim 23, wherein creatingthe context further comprises generating a frequent values list forwords in the history, and selecting words for the context from thehistory in dependence upon the frequent values list.
 27. The computerprogram product of claim 23, wherein creating the context furthercomprises generating a list of most recently used words in the history,and selecting words for the context from the history in dependence uponthe list of most recently used words.
 28. The computer program productof claim 23, wherein creating the context further comprises generating alist of words from the history used during a predetermined period oftime, and selecting words for the context from the history in dependenceupon the list of words from the history used during a predeterminedperiod of time.
 29. The computer program product of claim 23, whereinthe grammar is a VoiceXML grammar.
 30. The computer program product ofclaim 23, wherein the multimodal application runs on a voice server. 31.The computer program product of claim 23, wherein the computer programinstructions, when executed, further perform acts of: inferring at leastone phoneme for at least one word in the grammar using text to speechconversion; and adding the at least one phoneme for the at least oneword to the lexicon.
 32. The computer program product of claim 23,wherein the context comprises words taken from the at least one secondweb page.
 33. The computer program product of claim 23, wherein thecontext comprises words taken from at least one grammar for the at leastone second web page.